A heat exchanger device

ABSTRACT

The invention relates to a heat exchanger device including a plate heat exchanger having a plate package of heat transfer plates. Between the plates there are first passages ( 18 ) for a heat transfer medium and second passages ( 19 ) for a cooling agent. Porthole channels ( 21  and  22 ) communicate with the first passages. Porthole channels ( 23  and  34 ) communicate with the second passages. The porthole channel ( 21 ) forms at least a part of an inlet channel ( 31 ) for the heat transfer medium. The porthole channel ( 22 ) forms at least a part of an outlet channel ( 32 ) for the heat transfer medium. The porthole channel ( 23 ) forms a part of an inlet channel ( 33 ) for the cooling agent. The porthole channel ( 24 ) forms a part of an outlet channel ( 34 ) for the cooling agent. A conduit ( 5 ) extends to the inlet channel ( 33 ) for supplying the cooling agent to the second passages. The conduit includes a conduit portion ( 6 ) extending into and out of the outlet channel ( 34 ) for the heat exchanger between the cooling agent in the conduit portion and the cooling in the outlet channel.

TECHNICAL FIELD OF THE INVENTION

The present invention refers to a heat exchanger device including aplate heat exchanger, wherein the plate heat ex-changer includes a platepackage of heat transfer plates, which are arranged to form between theplates first passages for a heat transfer medium to be cooled and secondpassages for a cooling agent. The plate package includes a firstporthole channel and a second porthole channel, which communicate withthe first passages, and a third porthole channel and a fourth portholechannel, which communicate with the second passages. The first portholechannel forms at least a part of an inlet channel for supplying the heattransfer medium to the plate heat exchanger. The second porthole channelforms at least a part of an outlet channel for discharging the heattransfer medium from the plate heat exchanger. The third portholechannel forms at least a part of an inlet channel for supplying thecooling agent to the plate heat exchanger. The fourth porthole channelforms at least a part of an outlet channel for discharging the coolingagent from the plate heat exchanger. The heat exchanger device includesa conduit extending into the inlet channel for the cooling agent forsupplying the cooling agent to the third porthole channel and the secondpassages.

THE BACKGROUND OF THE INVENTION

The plate heat exchanger in such a heat exchanger device may be anevaporator used for production of cold in various applications, such asair-conditioning plants, cooling in food stores, cooling in industrialprocesses, etc. In typical cases, a heat transfer medium in the form ofa liquid, for instance water, is thereby to be cooled from a firsttemperature to a second. The temperature difference between thetemperature of the outgoing heat transfer medium and the temperature ofthe cooling agent is advantageously relatively small. It is importantthat the cooling agent in the evaporator, which provides the cooling ofthe heat transfer medium, is completely evaporated before it leaves theevaporator and is supplied to the compressor. If there are liquiddroplets left in the cooling agent, these droplets will damage thecompressor and reduce the efficiency and the lifetime of the compressor.

In order to avoid such liquid droplets in the cooling agent, it is knownto superheat the cooling agent at the cooling agent outlet of theevaporator. For instance, it is known to provide such a superheating bymeans of the liquid to be cooled, i.e. the incoming liquid is firstlyconveyed passing the outgoing cooling agent in order to raise thetemperature of the cooling agent. One problem in this context is to havea sufficient temperature difference between the incoming liquid and theoutgoing cooling agent. If this temperature difference is small, largeheat transfer surfaces are required, which leads to a large evaporator.

On the other hand it is important the superheating is not going too far.If the cooling agent supplied to the compressor has a high temperaturethe required compressing work is large, which makes the cooling processenergy-requiring.

PRIOR ART

EP-B-497 339 discloses a heat exchanger device having a plate heatexchanger used as evaporator in a cooling agent circuit. The plate heatexchanger includes a first plate part and a second plate part for theevaporation proper. In the first plate part the cooling agent to besupplied to the evaporator is conveyed in heat exchanging contact withthe cooling agent leaving the evaporator. The expansion valve of thecooling agent circuit is provided upstream the first part for theincoming cooling agent. A further valve for the incoming cooling agentis provided downstream the first plate part.

U.S. Pat. No. 5,678,419 discloses a similar heat exchanger device havinga plate heat exchanger used as evaporator in a cooling agent circuit.

EP-A-1 083 395 discloses a cooling agent circuit including anevaporator, a compressor, a condenser and an expansion valve. Thecooling agent leaving the condenser is conveyed in heat-exchangingcontact with the cooling agent leaving the evaporator and supplied tothe compressor.

DE-A-34 42 169 discloses a similar cooling agent circuit including anevaporator, a compressor, a condenser and an expansion valve. Thecooling agent leaving the condenser is conveyed in heat exchangingcontact with the cooling agent leaving the evaporator and supplied tothe compressor.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a heat exchangerdevice with a plate heat exchanger to be used as an improved evaporatorin a cooling agent circuit. A further object is to reduce the presenceof liquid droplets in the cooling agent leaving the plate heatexchanger. A further object is to provide an evaporator having a highefficiency. The further object is to provide an evaporator having alarge capacity in relation to the size of the evaporator. A furtherobject is to provide a heat exchanger device that has a simpleconstruction.

This object is achieved by the heat exchanger device initially defined,which is characterised in that said conduit includes a conduit portionextending into and out of the outlet channel for the cooling agent insuch a way that heat exchange takes place between the cooling agent insaid conduit portion and the cooling agent in the outlet channel.

The cooling agent is thus conveyed to its inlet channel and into theplate heat exchanger via the inventive conduit portion, which extendsinto and out of the outlet channel of the cooling agent. Consequently,the invention creates possibilities to raise the temperature of thecooling agent leaving the plate heat exchanger by means of the coolingagent located in the conduit portion. By means of the conduit portionaccording to the invention it is possible to prevent the cooling agentleaving the plate heat exchanger from containing liquid droplets. Thecooling agent in the conduit portion may have a high temperature, forinstance if the cooling agent located in the conduit portion arrivesdirectly from a condenser of a cooling agent circuit. The possibleliquid droplets which are too large or which have not yet beenevaporated in the plate heat exchanger will be finely distributed,evaporated and superheated in contact with the conduit portion. Sincethe liquid droplets in the cooling agent thus may be minimised both innumber and size, and the superheating is controlled, both the lifetimeand the efficiency of the compressor are increased.

An evaporator formed by the heat exchanger device according to theinvention has a higher capacity and/or efficiency than conventionalevaporators. It is possible to achieve a smaller temperature differencebetween the cooling agent and the out-going heat transfer medium thanfor conventional evaporators. In addition, the heat exchanger deviceaccording to the invention has a simple construction. The heat exchangerdevice according to the invention may be obtained by afterwardssupplementing a plate heat exchanger by the conduit portion as defined.

According to an embodiment of the invention, the outlet channel for thecooling agent includes the fourth porthole channel and a pipe extendingoutwardly from the fourth porthole channel and the plate package,wherein said conduit portion extends at least into and out of said pipe.Advantageously, said conduit portion may also expand into and out of thefourth porthole channel.

According to a further embodiment of the invention, said conduit portionextends in a U-shaped path in the outlet channel. In order to increasethe heat transfer to the cooling agent leaving the plate heat exchanger,said conduit portion may include surface enlarging members provided onthe conduit portion and extending in the outlet channel. Such surfaceenlarging members may include flanges. Furthermore, it is possible tolet said conduit portion extend in a path which is significantly longerthan the double distance between an entrance position for the entranceof the conduit portion in the outlet channel and a position of theconduit portion located as far as possible away from the entranceposition. For instance, said conduit portion may extend in azigzag-shaped or helical-shaped path in the outlet channel.

According to a further embodiment of the invention, said conduit isincluded in a cooling agent circuit which includes a compressor, acondenser, and expansion valve and an evaporator that includes the plateheat exchanger. Said conduit portion is located between the condenserand the expansion valve.

According to a further of embodiment of the invention, the inlet andoutlet channels are provided in such a way that the heat transfer mediumflows through the first passages in a counterflow direction or parallelflow direction in relation to the cooling agent in the second passages.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now to be explained more closely through adescription of various embodiments shown by way of example and withreference to the drawings attached hereto.

FIG. 1 discloses a functional diagram of a heat exchanger deviceaccording to the invention.

FIG. 2 discloses schematically a front view of a plate heat exchanger ofthe heat exchanger device in FIG. 1.

FIG. 3 discloses schematically a side view of the plate heat exchangerin FIG. 2.

FIG. 4 discloses schematically a side view of an embodiment of a conduitportion of the heat exchanger device.

FIG. 5 discloses schematically a side view of another embodiment of aconduit portion of the exchanger device.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION.

FIG. 1. discloses a heat exchanger device including a cooling agentcircuit with a compressor 1, a condenser 2, an expansion valve 3 and anevaporator 4. The evaporator 4 is designed as a plate heat exchanger tobe described more closely below. A cooling agent is conveyed in aconduit 5 between the different components 1-4 in the cooling agentcircuit. The conduit 5 includes a conduit portion 6, which is locatedbetween the outlet of the condenser 2 and the inlet of the expansionvalve 3. The cooling agent in the conduit portion 6 is conveyed in heatexchanging contact with the cooling agent in the proximity and withinthe outlet of the evaporator 4.

FIGS. 2 and 3 discloses a plate heat exchanger 10, which forms theevaporator 4 in the heat exchanger device in FIG. 1 the plate heatexchanger 10 includes a plate package 11 with heat exchanger plates 12provided adjacent to each other. The plate package 11 is providedbetween two end plates 13 and 14. The end plates 13 and 14 are pressedagainst the plate package 11 and each other by means of tie-bolts 15extending through the end plates 13 and 14. The tie-bolts 15 includesscrew-threads and the plate package 11 may thus be compressed by nuts 16threaded on to the tie-bolts 15 in a manner known per se. In theembodiment disclosed, four tie-bolts 15 are indicated. It is to be notedthat the number of tie-bolts 15 may vary in different applications.Alternatively, the plates 12 together with the end plates 13 and 14 maybe brazed to a plate package where the braze joints keep the platepackage together and maintain the pressure.

The heat exchanger plates 12 are arranged in such a way that firstpassages 18 and second passages 19 are formed between the plates 12. Thefirst passages 18 are intended to convey a heat transfer medium to becooled and the second passages 19 are intended to convey a coolingagent. The plate package 11 includes a first porthole channel 21 and asecond porthole channel 22, a third porthole channel 23 and a fourthporthole channel 24. The first porthole channel 21 and the secondporthole channel 22 communicate with the first passages 18. The thirdporthole channel 23 and the fourth porthole channel 24 communicate withthe second passages 19. The first porthole channel 21 forms at least apart of an inlet channel 31 for supplying the heat transfer medium tothe plate heat exchanger 10. The second porthole channel 22 forms atleast a part of an outlet channel 32 for discharging the heat transfermedium from the plate heat exchanger 10. The third porthole channel 23forms at least a part of an inlet channel 33 for supplying the coolingagent to the plate heat exchanger 10. The fourth porthole channel 24forms at least a part of an outlet channel 34 for discharging thecooling agent from the plate heat exchanger 10. In the embodimentdisclosed in FIGS. 2 and 3, the heat transfer medium will thus flowthrough the first passages 18 in a counterblow direction in relation tothe cooling agent in the second passages 19. Alternatively, the heatexchanger device may designed in such a way that the heat transfermedium will flow through the first passages 18 in a parallel flowdirection in relation to the cooling agent in the second passages 19.

As can be seen in especially FIG. 3, the conduit 5, with the conduitportion 6, extends, compare FIG. 1, in a path into and out of the outletchannel 34 for the cooling agent. The conduit 5 extends further to theconduit portion 6, compare FIG. 1, to the expansion valve 3. The conduit5 extends from the expansion valve 3 into the inlet channel 33 for thecooling agent for supplying the cooling agent to the third portholechannel 23 and the second passages 19. Thanks to the conduit portion 6in the outlet channel 34, a heat exchange will take place between therelatively warm cooling agent in the conduit portion 6 and thesubstantially evaporated, relatively cold cooling agent in the outletchannel 34.

As further can be seen clearly from FIG. 3, the outlet channel 34 forthe cooling agent includes the fourth porthole channel 24 and a pipe 36extending outwardly from the fourth porthole channel 34 and the platepackage 11. In accordance with the embodiment disclosed herein, theconduit portion 6 extends in both the pipe 36 and the fourth portholechannel 24. It is to be noted that the conduit portion 6 also may extendmerely in the pipe 36 but not in the porthole channel 24 proper.Furthermore, it is possible to dispense with the pipe 36 and thus letthe conduit portion 6 merely extend into and out of the porthole channel24 proper. In the embodiment disclosed herein, the outlet channel alsoincludes a prolongation pipe 37 extending from the pipe 36. However, theconduit portion 6 connects to the pipe 36 in such a way that the conduitportion 6 does not extend in the prolongation pipe 37.

As can be seen from FIG. 3, the conduit portion 6 extends in a U-shapedpath in the outlet channel 34 for the cooling agent. As can be seen fromFIG. 4, the conduit portion 6 may advantageously but not necessarilyinclude surface-enlarging members, for instance in the form of flanges38, which are provided on the conduit portion 6 and extend substantiallyradially outwardly from the conduit portion 6. By such surface-enlargingmembers, the heat transfer from the cooling agent from the condenser 2to the cooling agent leaving the evaporator may be improved. Accordingto an alternative embodiment illustrated in FIG. 5, the conduit portion6 may extend in a path which is significantly longer than the doubledistance between an entrance position for the entrance of the conduitportion 6 in the outlet channel 34 and a position of the conduit portion6 located as far as possible away from the entrance position in theoutlet channel 34. As can be seen from FIG. 5, the conduit portion 6 maythan extend in a reciprocating path, for instance a zigzag-shaped pathin the outlet channel 34. Alternatively, the conduit portion 6 mayextend in a helical-shaped path in the outlet channel 34. It is alsopossible to achieve such a surface-enlarging effect in other ways, forinstance through embossing of the surface of the conduit portion 6.

The heat exchanger device also includes a sensor device 41 provided ator in the outlet channel 34 for the cooling agent. The sensor device 41includes sensors for sensing the temperature and the pressure of thecooling agent discharged from the plate heat exchanger 10. In theembodiment disclosed in FIGS. 2 and 3, the sensor device 41 is providedin the prolongation pipe 37, i.e. at a certain distance from the conduitportion 6. The sensor device 41 is connected to the expansion valve 3for controlling the opening degree of the expansion valve 3 dependent onthe pressure and the temperature of the outgoing cooling agent. The flowof the cooling agent into the evaporator 4 may thus be controlled viathe expansion valve 3 which may include a pressure valve. The heatexchanger device according to the invention improves the stability ofthe superheating, which facilitates the control of the expansion valve 3by means of the sensor device 41.

The invention is not limited to the embodiments disclosed but may bevaried and modified within the scope of the following claim.

1.-11. (canceled)
 12. A heat transfer device comprising a plate heatexchanger, wherein the plate heat exchanger includes a plate package ofheat transfer plates, which are arranged to form between the platesfirst passages for a heat transfer medium to be cooled and secondpassages for a cooling agent, wherein: the plate package includes afirst porthole channel and a second porthole channel, which communicatewith the first passages, and a third porthole channel and a fourthporthole channel, which communicate with the second passages; the firstporthole channel forms at least a part of an inlet channel to supply theheat transfer medium to the plate heat exchanger; the second portholechannel forms at least a part of an outlet channel to discharge the heattransfer medium from the plate heat exchanger; the third portholechannel forms at least a part of an inlet channel to supply the coolingagent to the plate heat exchanger; the fourth porthole channel forms atleast a part of an outlet channel to discharge the cooling agent fromthe plate heat exchanger; the heat exchanger device includes a conduitextending into the inlet channel for the cooling agent to supply thecooling agent to the third porthole channel and the second passages, andwherein the conduit includes a conduit portion extending into and out ofthe outlet channel for the cooling agent such that heat exchange takesplace between the cooling agent in the conduit portion and the coolingagent in the outlet channel.
 13. A device according to claim 12, whereinthe outlet channel for the cooling agent includes the fourth portholechannel and a pipe which extends outwardly from the fourth portholechannel and the plate package, wherein the conduit portion extends atleast into and out of the pipe.
 14. A device according to claim 13,wherein the conduit portion extends into and out of the fourth portholechannel.
 15. A device according to claim 12, wherein the conduit portionextends in a U-shaped path in the outlet channel.
 16. A device accordingto claim 12, wherein the conduit portion includes surface enlargingmembers, which are provided on the conduit portion and extend in theoutlet channel.
 17. A device according to claim 16, wherein the surfaceenlarging members include flanges.
 18. A device according to claim 12,wherein the conduit portion extends in a path which is significantlylonger than double the distance between an entrance position for theentrance of the conduit portion into the outlet channel and a positionof the conduit portion located as far as possible from the entranceposition.
 19. A device according to claim 12, wherein the conduitportion extends in a zigzag-shaped or helical-shaped path in the outletchannel.
 20. A device according to claim 12, wherein the conduit isincluded in a cooling agent circuit, which includes a compressor, acondenser, an expansion valve and an evaporator that includes the plateheat exchanger.
 21. A device according to claim 20, wherein the conduitportion is located between the condenser and the expansion valve.
 22. Adevice according to claim 12, wherein the inlet and outlet channels arearranged such that the heat transfer medium flows through the firstpassages in a counterflow direction or a parallel flow direction inrelation to the cooling agent flow in the second passages.